The present invention relates to a small-scaled inductance element and its preparation method, especially to a method of encapsulating an inductive coil by plating a magnetic material thereon and the inductance element so prepared.
The term xe2x80x9cinductance elementxe2x80x9d generally refers to elements such as inductor and transformer. The structure of an inductance element comprises a coil structure and a core. If a transformer is the case, it is used to transform a voltage or a current into another voltage or a current. Ideally, its transformation rate is preferably 100% and its volume and weight are zero. However, it is already known from the prior art that the transformation rate is influenced by material of core and process of manufacture.
In the prior art, materials for core included silicon steel plate and soft magnetic material such as Ferrite and Permalloy. The soft magnetic material provides higher magnetic flux density endurance capability. Although the cost of soft magnetic material is relatively higher, it is frequently used in the industry due to its lower material consuming and lighter weight.
In the preparation of the inductance element, the core structure may be prepared with multiple levels of silicon steel sheets or Permalloy sheets. A sheet structure provides larger effective area of magnetic circuit. In the prior art, however, the volume and weight of the core is still a problem to be solved.
In addition to this, the winding process of the coil is a time consuming process in the preparation of the inductance element. In order to simplify the preparation of the inductance element, a printed circuit board approach was developed. In U.S. Pat. No. 5,761,791 (issued to Bando) disclosed a technology in which two coil structures were first prepared on a printed circuit board and sintered cores made of Ferrite or Permalloy are then affixed to the coil to form a transformer. In the Bando invention, however, the core is sintered during the preparation. As a result, only cores with E-shape or O-shape may be prepared. The effective area of the magnetic circuit is relatively low. On the other hand, because the cores are affixed to the coils, the shape of the core is limited by the requirements in the assembly process. For example, the ideal shape of the cores should be loop shape. A loop-shaped core is difficult to be positioned and assembled. In order to facilitate the assembly, the core is preferably E-shape or I-shape. Waste of material is thus caused.
Nevertheless, when the cores are affixed to the coils, gaps and spaces are left between them. The gaps and spaces cause large leakage of the flux and heating. In addition, cores prepared with sintering perform high contraction rate, so that deformations are always found. Such characters damage the yield rate of the inductance element. Other problems of this technology include expensive manufacture costs. This is because different molds shall be prepared for different transformers so that the cores may be sintered inside the molds.
It is thus a need in the industry to have a simplified preparation method for small-scale inductance element.
It is also a need in the industry to have a novel preparation method for small-scale inductance element where no sinter and adhesion processes are needed.
It is also a need to have a novel preparation method for small-scale inductance element where shapes of components are not limited by the process used.
It is also a need to have a novel preparation method for small-scale inductance element so that inductance elements with high efficiency and yield rate may be obtained.
The objective of this invention is to provide a novel and simplified preparation method for small-scale inductance element.
Another objective of this invention is to provide a novel preparation method for small-scale inductance element where no sinter and adhesion processes are needed.
Another objective of this invention is to provide a preparation method for inductance element where shapes of components are not limited by the process used.
Another objective of this invention is to provide a preparation method for inductance element so that inductance elements with high efficiency and yield rate may be obtained.
Another objective of this invention is to provide a method for preparation of inductance element with multiple-layered cores.
Another objective of this invention is to provide a novel structure of inductance element.
Another objective of this invention is to provide an inductance element with simplified preparation process and enhanced working efficiency.
Another objective of this invention is to provide an inductance element with higher yeild rate.
According to this invention, a novel inductance element and its preparation method are disclosed. The inductance element of this invention comprises at least one coil structure, an insulation layer, a conductive metal layer and a least one metal core structure. In the preparation method for inductance element of this invention, at least one coil structure is prepared and at least one core structure is prepared with the plating technology. An intermittent plating approach is used to prepare the cores so that a core structure with multiple layers may be obtained. The coil structure applicable to this invention includes one prepared on a printed circuit board or a winded enameled wire coil structure. When a group of two coils is prepared, the inductance element may function as a transformer.
When a transformer is to be prepared, the permeability s of the core structure and the coil structure are first considered. Suited material for the core structure and the coil structure include Ferrite (with a permeability of about 500 to 1300) and Permalloy (with a permeability of above 2000).
The above and other objectives and advantages of this invention may be clearly understood from the detailed specification by referring to the following drawings.